Connecter for edgewise wound coils



May 18, 1937. FRESE 2,081,089

CONNECTER FOR EDGEWISE WOUND COILS Filed Nov. 6, 1935 Patented May 18,1937 UNITED STATES PATENT OFFICE 2,081,089 CONNECTER FOR EDGEWISE WOUNDCOILS Application November 6 Claims.

This invention relates to connecters for attaching conductors I to theconvolutions of resistor elements composed of metal ribbons woundhelically on edge. Connecters in the form of clamps which griptheopposite faces of a coil, as illustrated in patent to George H.Whittingham 1,550,640, have been commonly'used, and these have theadvantage of a large contact area between the clamping members and thecoil and are satisfactory if the parts of the connecter are clamped sotightly and evenly against the coil as to ensure contact throughout sucharea; but owing to springing of the metal or imperfect fitting of theparts of the clamp against the sides of the coil, the contact throughoutthe area. of the clamping members is often not attained.

In carrying out my invention, I provide a connecterwhich grips the innerand outer edges of the edgewise wound coil with a strong wedging actionwhich causes the gripping surfaces to impinge against and bite into thethin edges of the coil, thus ensuring a good electrical contact in everycase, even though the gripping surfaces are smaller than is the casewith the flat clamps above mentioned.

In the accompanying drawing,

I Fig. 1 is a plan view of an edgewise wound coil with one of theconnecters, in its preferred form,

attached thereto;

Fig. 2 is a side elevation of the connecter applied to the coil, lookingfrom, left to right in Fig. 1;

Fig. 3 is a section on the line 3-3 of Fig. 2;

Fig. 4 is a perspective view of the wedge piece and body of theconnecter, separated;

Fig. 5 is a side elevation of a modified form of connecter applied to acoil;

Fig. 6 is a perspective viewof the wedge piece and body of the connectershown in Fig. 5, separated;

Fig. 7 is a section on the line 'I-,-'I of Fig. 5;

Fig. 8 is a side elevation of another modified form of connecter,attached to a coil;

Fig. 9 is a perspective view of the. parts of the connecter shown inFig. 8, separated, and,

Fig. 10 is a section on the line I0i0-of Fig. 8.

Referring to Figs. 1-4, inclusive, of the drawing, A indicates thepreferred form of connecter, and B indicates an edgewise wound helixmounted upon a suitable insulating support 1 onto which the helix isthreaded. The connecter comprises a body it, a wedge piece a. and a bolt2 for forcing the wedge piece against the body, .the bolt also servingas a securing means for a conductor e which it may be desirable toelectrically 6, 1935, Serial No. 48,585

connect to the coil. The body is relatively flat except for a hook 3 atone end and a curved flange 4 extending around the opposite end on thesame side of the body as the hook. The side edges of the body tapertoward its hooked end as shown 5 and the end of the tapered portion isdoubled backwardly over the body to form the hook. The central part ofthe flange is directly opposite the hook and adjacent this central partand in line with the hook is a threaded opening 5 adapted 10 to receivethe bolt 2. At the opposite sides of a line passing through the centerof the flange and of the bolt hole and hook, the body has longitudinalslots 6. The body as well as the wedge piece are conveniently made ofmetal stampings, and in making the body the central portion of theflange is formed so that its inner wall 4 slopes at a slightly obtuseangle to the flat surface of the body.

The wedge piece 0. consists of a flat metal strip, substantiallystraight on one edge, bent into U-form, with similar parallel arms Ihaving lugs l projecting from the straight edge of the strip near theends of 1 the arms and adapted to extend into the slots 6 when the wedgepiece is in place on the body. The opposite edges of the arms arepreferably made convex between the lugs and the curved part of thestrip, as shown at 1 and the curved part 1 is preferably inclined at aslightly obtuse angle with respect to the lower edge of the strip so asto conform to the inclination of the inner wall'of the flange 4 of thebody. The bolt extends between the arms of the wedge piece into thethreaded opening in the body and a washer 8 under the bolt head isadapted to bear against the convex edges of the arms and force the wedgepiece toward the body when the bolt is tightened. To secure theconnecter shown in Figs. 1 to 4 to a coil of the resistor element, thebolt is partly unscrewed and the hooked end of the body is insertedbetween the coils adjacent the one, as b, to which it is desired toattachthe connecter. It is then pulled outward to engagethe hook withthe inner edge of the coil, as shown in Figs. 2 and 3. The wedge pieceis then passed under the bolt headinto the position where the lugs I arewithin'the slots 6 in the body and the curved inclined face of the wedgepiece is against the inclined face of the flange. The lugs will then beclose to the outer edge of the coil b and the. ends of the arms I willlie against the face of said coil. The bolt is then tightened againstthe wedge piece and because of the coengaging inclined surfaces of thewedge piece and flange, the wedge piece will be forced toward the hookand the coil will be gripped tightly at its edges by the hook and thelugs on the wedge piece, the latter engaging the outer edge of the coil.At the same time, the ends of the wedge piece beyond the lugs will beforced tightly against the face of the coil and the latter will beclamped against the flat portion of the body, so that the connecter willbe held firmly on the coil. While clamping the coil at its sides adds tothe electrical conductivity of the joint, the forceful gripping of thecoil at its edges makes a much more perfect electrical connectionbetween the connecter and the coil. The convex surfaces of the arms ofthe wedge piece ensure a relatively small contact with the washer on thebolt so that as the bolt is tightened the wedge piece may slide towardthe coil without being hindered by a large surface contact with thewasher or bolt head.

The connecter C, shown as a modification in Figs. 5, 6, and 7, comprisesa body which, in so far as the hook 9, flange I0 and threaded bolt holeii are concerned, are substantially the same as in the body a of thepreviously described figures. Instead of having two slots for receivinglugs on the wedge piece, as described in the previous figures, the bodyof the connecter has a single wide slot l2 between the bolt hole andhook to receive a single relatively wide lug l3 on the wedge piece 0'.The U-shaped wedge piece a of Figs. 1 to 4 might be used with the bodyof Figs. 5 to 7 because the two lugs on the arms of the U-shaped piecewould fit within and be guided by the ends of the wide slot l2. Thewedge piece 0 is a solid piece having a slightly elongated bolt hole i4through which the bolt l5 extends into the threaded opening in the bodyand it has a slightly inclined curved end l6 adapted to fit against theinclined inner face of the flange. The part of the wedge piece I!through which the bolt extends is circular in form and the part 5'!which carries the lug and engages the coil is shown with parallel sideedges, the Width of this part being, for convenience of manufacture, thesame as the length of the lug. The surface of the wedge piece which isengaged by the washer on the bolt is made convex, as in the previouslydescribed figures and for the same purpose.

In this form of connecter, the wedge piece cannot be removed or appliedto the body without removing the bolt. When assembled, the connecter canbe applied to a coilby unscrewing the bolt far enough to allow the wedgepiece to be turned thereon, then engaging the hook with the inner edgeof the coil and then moving the wedge piece into its position with thelug thereon in the slot 12, and then tightening the bolt to force thelug on the wedge piece against the outer edge of the coil. The slightlyenlarged bolt hole l2 allows the wedge piece to move toward the coilwithout obstruction by the bolt.

The connecter D, shown in Figs. 8 to 10, comprises the body (I havingthe hook l9 at one end and the curved flange at the opposite end, thelatter having the inclined wall'20 as in the previously describedfigures, and it has the threaded bolt hole 2| to receive the bolt 22, asin said figures. The wedge piece d has a semicircular end with aninclined edge adapted to engage the inclined surface of the flange andit has an elongated opening 23 through which the bolt extends. The bodyis not provided with a slot or slots to receive lugs on the wedge piece,as in the previously described figures. The side edges 24 of the bodybetween its curved portion and the hook are straight and parallel, andthe wedge piece diverges from its curved end and extends laterallybeyond said edges in triangular form. At its widest part, lugs 25 areprovided, these lugs being close to the side edges 24 of the body so asto be guided thereby, and having curved edges 25 for engaging the outeredge of the coil. The application of the connecter to the coil is madeby unscrewing the bolt so that the wedge piece can turn thereon; thenengaging the hook with the inner edge of the coil, then turning thewedge piece into the position where the lugs are at opposite sides ofthe wedge piece and in position to engage the outer edge of the coil,and then tightening the bolt to cause the wedging action which forcesthe lugs against the edge of the coil. The coil is then clamped at itssides between the body of the connecter and the end portion of the wedgepiece which lies between the lugs.

While I have described the connecters as applied to the convolutions ofan edgewise wound coil, it is evident that they may be applied to theflat resistance ribbon of which the coils are made,

such as straight extensions of the ribbon at the ends of the coil.

What I claim is:

1. A connecter for edgewise wound resistor coils comprising a relativelyflat body having a hook at one end adapted to engage the inner edge of acoil and a curved flange at its opposite end having its concave surfaceopposed to said hook, said body having also a threaded opening adjacentthe flange and having a slot in that part between the said opening andthe hook, a wedge piece having a curved surface at one end engaging theconcave surface of the flange and having a lug projecting through saidslot and adapted to engage the outer edge of the coil, one of saidsurfaces being inclined with respect to the plane of the body, and abolt extending into said threaded opening and adapted to clamp the wedgepiece against the body.

2. A connecter for edgewise wound resistor coils comprising a relativelyflat body having a hook at one end adapted to engage the inner edge of acoil and a curved flange at its opposite end having its concave surfaceopposed to said hook and inclined at an obtuse angle with respect to theplane of the body, said body having also a threaded opening adjacent theflange and having a pair of laterally spaced slots in that part betweensaid opening and the hook, a wedge piece comprising a U-shaped metalstrip having its central part engaging the concave surface of the flangeand having lugs projecting from its arms through said slots and adaptedto engage the outer edge of the coil, and a bolt extending between thearms of the wedge piece into said threaded opening and adapted to clampthe Wedge piece against the body.

3. A connecter for edgewise wound coils comprising a flat body having ahook at one end adapted to engage the inner edge of the coil and havinga curved flange extending around its opposite end and opposed to saidhook, the inner face of said flange sloping toward the body, said bodyhaving also a threaded opening therethrough adjacent the central portionof the flange and having longitudinal slots in its central portionspaced laterally apart, and a wedge member comprising a U-shaped metalstrip having its central portion adapted to fit against the sloping faceof the flange and the ends of its arms adapted to lie against the sideof the coil and having projections adjacent said ends fitting in saidslots and adapted to engage the outer edge of the coil, and a boltextending between the arms of said wedge piece into said threadedopening and adapted to force the wedge piece toward the body.

4. A connector for edgewise wound coils comprising a flat body having ahook at one end adapted to engage the inner edge of the coil and havinga curved flange extending around its opposite end and opposed to saidhook, the inner face of said flange sloping toward the body, said bodyhaving also a threaded opening therethrough adjacent the central portionof the flange and having a transverse slot in its central portion, and awedge piece having a rounded end adapted to fit against the sloping faceof the flange and its opposite end adapted to lie against the side ofthe coil and having a projection extending into said slot and adapted toengage the outer edge of the coil, said wedge piece having also anopening therethrough larger than said threaded opening and a boltextending through the opening in the wedge piece and into said threadedopening in the body and adapted to force the wedge piece toward thebody.

5. A connecter for edgewise wound coils comprising a flat body having ahook at one end adapted to engage the inner edge of the coil and havinga curved flange extending around its opposite end and opposed to saidhook, the inner face of said flange sloping toward the body, said bodyhaving also a threaded opening therethrough adjacent said centralportion of the flange and a wedge piece having a rounded end adapted tofit against the sloping face of the flange and having its opposite endadapted to lie against the side of the coil and having spacedprojections at the latter end adapted to engage the outer edge of thecoil, said wedge piece having an opening therethrough larger than saidthreaded opening, and a bolt extending through the opening in the wedgepiece and into said threaded opening in the body and adapted to forcethe wedge piece toward the body.

6. A connecter for flat resistor ribbons comprising a relatively flatbody having a hook at one end adapted to engage one edge of the ribbonand a flange at its opposite end having a surface opposed to said hook,a wedge piece having a surface at one end adapted to bear against saidsurface of the flange, one of said surfaces being inclined with respectto the plane of the body, said wedge-piece having adjacent its oppositeend a lug or shoulder projecting laterally from one side thereof adaptedto bear against the opposite edge of the ribbon and having a partadapted to overlap and lie against one side of the ribbon, and means forclamping the wedgepiece against the body.

JOSEPH F. FRESE.

